The transformation of light energy into electrical energy using photovoltaic (PV) systems has been known for a long time and these photovoltaic systems are increasingly being implemented in residential, commercial, and industrial applications. Although developments and improvements have been made to these photovoltaic systems over the last few years to improve their efficiency, the efficiency of the photovoltaic systems is still a focal point for continuing to improve the economic viability of photovoltaic systems.
Photovoltaic systems typically include, among other components, a photovoltaic array that generates DC power and an inverter that converts the DC power to AC power (e.g., single or three phase power). It is often desirable to design and operate photovoltaic arrays so that the voltage that is output is relatively high, and hence current is low, in order to reduce costs associated with high-current elements and to reduce energy losses.
Photovoltaic arrays that include crystalline (e.g., monocrystalline or polycrystalline) silicon, for example, may operate in an open load state at 1200 Volts and amorphous silicon may operate in an open load state at 1400 Volts. Although arrays are capable of applying high open loaded voltages, arrays rarely do so because once power is drawn from the arrays, the loaded voltage of the array drops substantially. For example, under loaded conditions, crystalline silicon arrays may operate at between 780 to 960 volts and amorphous silicon may operate around 680 Volts.
Inverters are available in a variety of voltage ratings to accommodate the infrequently encountered unloaded voltage conditions of the array. But inverters that are rated for higher voltages typically cost more and operate less efficiently than inverters that are designed to operate at lower voltages. And as a consequence, inverters are often designed with silicon that is less efficient and costlier than silicon that could be used if the inverter did not have to be designed to handle high, open load voltages. For example, inverters incorporating silicon rated for voltages around 1400 Volts incur substantially more losses, and cost substantially more than inverters that utilize silicon that is rated for 1200 Volt applications.